准东煤在常规燃烧利用过程中出现严重的积灰结渣和CO₂排放等问题，极大地限制了其低碳清洁高效利用。采用中低温热解低阶煤生产半焦、焦油和热解气是煤炭分质分级利用的龙头技术，准东高碱煤热解半焦气化活性高，采用化学链燃烧方式有利于实现其低碳清洁高效转化。以CO₂为气化介质，赤铁矿石为载氧体，在固定床上开展准东煤半焦原位气化化学链燃烧特性研究，并探究了准东煤半焦中碱(土)金属(AAEMs)的迁移转化规律。研究表明，赤铁矿载氧体能够显著提高固定床反应器出口烟气中CO₂体积分数，然而随着载氧体与半焦质量比(m_OC/m_C)不断增加，CO₂体积分数先急剧增加而后趋于不变，最佳的m_OC/m_C为50∶1，而700 ℃热解制取的准东煤半焦经酸洗脱灰处理后固定床反应器出口相应烟气中CO₂的选择性降低了8.95%，这表明准东煤半焦中具有催化活性的AAEMs显著影响其化学链燃烧性能。赤铁矿载氧体对准东煤半焦表面AAEMs的分布也有显著影响，与未加入时相比，Na、K元素在半焦表面呈现较为明显的团簇富集，Ca、Mg元素在空间分布上呈更为明显的依赖关系。采用原位气化化学链燃烧方式后准东煤半焦中的AAEMs向赤铁矿载氧体中发生迁移与转化，并生成霞石(NaAlSiO₄)、钾长石(KAlSi₃O₈)、钙铝黄长石(Ca₂Al₂SiO₇)、镁橄榄石(Mg₂SiO₄)等高熔点矿物质，有效抑制了准东煤半焦中AAEMs向气相的挥发。

The low-carbon, clean, and efficient utilization of the Zhundong coal is greatly limited by some severe problems such as ash accumulation, slagging, and CO₂ emissions in the conventional combustion and utilization processes. The adoption of low-rank coal pyrolysis at low and moderate temperatures to produce semicoke, tar, and pyrolysis gas is a leading technology for the utilization of classified coal. Based on the characteristic of high alkali gasification activity of pyrolysis semicoke, the chemical-looping combustion technology is adopted to achieve a low-carbon, clean, and efficient conversion of the Zhundong coal semicoke. The in-situ gasification chemical-looping combustion characteristics of the Zhundong coal semicoke are studied in a fixed bed, in which CO₂ is selected as the gasification agent and hematite is considered as the oxygen carrier. The study of migration and transformation laws of alkali and alkaline earth metals (AAEMs) in the Zhundong coal semicoke also is performed. The experimental result indicates that the addition of the hematite oxygen carrier can significantly improve the CO₂ concentration of the flue gas at the outlet of the fixed bed reactor. However, CO₂ concentration increases first and then remains constant with the increase in the mass ratio of the oxygen carrier and semicoke (m_OC/m_C). The optimal m_OC/m_C is determined as 50∶1. In this case, the CO₂ selectivity of the flue gas at the outlet of the fixed-bed reactor is decreased by 8.95 percentage points at the pyrolysis temperature of 700 ℃ after acid washing and deashing treatment, indicating that the chemical-looping combustion performance of the Zhundong coal semicoke can be significantly affected by the catalytic activity of AAEMs in the semicoke. The distribution of AAEMs on the surface of the Zhundong coal semicoke is affected by the hematite oxygen carrier. Compared with the absence of the hematite oxygen carrier, more obvious cluster enrichment on the surface of semicoke for Na and K elements is found. An obvious dependency relationship for the distribution of Ca and Mg elements is observed. When the in-situ gasification chemical-looping combustion is adopted, the active AAEMs elements in the semicoke are migrated and transformed into hematite. High melting point minerals such as nepheline (NaAlSiO₄), potassium feldspar (KAlSi₃O₈), gehlenite (Ca₂Al₂SiO₇), and magnesium olivine (Mg₂SiO₄) are generated, effectively suppressing the volatilization of AAEMs in the Zhundong coal semicoke.